A mask vapor deposition method or an etching method by photolithography is mainly used for the pattern formation of electrodes or functional thin films in the manufacturing process of electronic devices. Problems such as the difficulty of upsizing boards and complicated processes have been indicated in these related-art methods.
Recently, the application of a divisional coating technique utilizing wettability deference of liquids to the patterning of functional thin films has been developed instead of using these related-art methods. This divisional coating technique is a method for producing electronic devices such as an organic electroluminescence (EL) element and an organic field-effect transistor (FET) element by forming a patterning layer including an easy-to-wet region and a difficult-to-wet region on the surface of a substrate, and then applying and drying the solution of a functional thin film forming material on this patterning layer to form a functional thin film only on the easy-to-wet region.
For such a patterning layer for a functional thin film, a layer made by irradiating a photocatalyst-containing layer made of titanium dioxide and organopolysiloxane with ultraviolet light through a mask (for example, refer to Patent Document 1), a layer made by irradiating a layer made of a compound having light-absorbing parts, such as dyes, and fluorine-containing polymer with a laser or with ultraviolet light through a mask (for example, refer to Patent Document 2) are known, for example. In addition, also developed is a method of forming the patterning layer by vapor deposition of a fluorine based coating agent through a mask (for example, refer to Patent Document 3).
Patterning layers developed to date, such as layers described in the Patent Documents, remain in the element even after the patterning of functional thin films is completed. Therefore, this patterning layer needs to have durability to subsequent processes and reliability of not providing adverse effects to the properties of an electronic device when the patterning layer is in the electronic device. Such required properties of the patterning layer vary depending on devices manufactured or the place to use the patterning layer. Among them, an electrical insulation property is the important required property to the patterning layer of an electrode.
Techniques developed to date have only focused on properties as a patterning layer. Therefore, for example, when a source electrode and a drain electrode of an organic FET element are patterned, a gate insulating film needs to be separately prepared under the patterning layer.
By contrast, polyimides have excellent heat resistance, mechanical strength, electrical insulation properties, chemical resistance and the like. Therefore, polyimides are used for various electronic devices. For an example of using a polyimide for a patterning layer, a layer using a tetracarboxylic acid anhydride having an aliphatic ring structure (for example, Patent Document 4) has been disclosed. However, long time exposure treatment is necessary for these examples because these materials require extremely large amounts of ultraviolet ray irradiation.
Patent Document 1: Japanese Patent Application Publication No. JP-A-2000-223270
Patent Document 2: Japanese Patent Application Publication No. JP-A-2004-146478
Patent Document 3: Japanese Patent Application Publication No. JP-A-2004-273851
Patent Document 4: Japanese Patent Application Publication No. JP-A-2006-185898